The disclosure relates to substrates exhibiting anti-glare properties and more particularly to substrates exhibiting low sparkle, low distinctiveness of image (DOI), and low transmission haze.
Advances in consumer electronic technology has necessitated improvements in various cover substrate properties. One such area for improvement is anti-glare surfaces for consumer electronic devices such as smart (mobile) phones, tablets, electronic readers, displays and TVs.
Known anti-glare surfaces often have textured surfaces that are formed by forming crystals on the surface of the substrate and etching portions of the substrate not covered by the crystals. In some instances, hydrofluoric acid (HF), ammonium bifluoride (NH4HF2), propylene glycol (PG), and a mineral acids (such as sulfuric acid, H2SO4) are utilized to form such anti-glare surfaces on glass substrates.
For consumer electronic applications, known anti-glare surfaces can exhibit sparkle (or a grainy appearance) at low transmittance haze levels (e.g., about 10% or less). Display “sparkle” is a phenomenon that can occur when anti-glare or light scattering surfaces are incorporated into a display system. Sparkle is associated with a very fine grainy appearance that can appear to have a shift in the pattern of the grains with changing viewing angle of the display. This type of sparkle is observed when pixelated displays such as LCDs are viewed through an antiglare surface. Such sparkle is of a different type and origin from “sparkle” or “speckle” that has been observed and characterized in projection or laser systems
As displays exhibit higher definition and more pixels are assembled at higher densities, the reduction of sparkle becomes more important. Accordingly, there is a need for anti-glare surfaces that exhibit low sparkle, while still exhibiting low DOI and low transmission haze.